How many killer hurricanes will it take before America gets serious about global warming? It’s hard to imagine a more clear-cut wake-up call than Hurricane Katrina; environmentally speaking, it was nearly the perfect storm. In a single catastrophic event, it brought together the most urgent environmental problem of our time–global warming–with the most telling but least acknowledged environmental truth: When the bill for our collective behavior comes due, it is invariably the nonwhite, nonaffluent members of society who pay a disproportionate share. And who said Mother Nature has no sense of irony? Katrina (and then Rita) struck at a major production site for America’s oil and natural gas–the two carbon-based fuels that, along with coal, help drive global warming.

What’s more, Katrina’s primary target already ranked as the most environmentally ravaged state in the union. Louisiana is home to “Cancer Alley,” a 100-mile stretch between New Orleans and Baton Rouge that contains the greatest concentration of petrochemical factories in the United States. Pollution from those factories has punished nearby communities–again, mainly poor and black–for decades, as Steve Lerner documented in his recent book Diamond. This pollution has also drained into the Mississippi River, where it joins fertilizer and pesticide runoff from millions of acres of Midwestern farmland to flow into the Gulf of Mexico, creating a massive “dead zone” off the Louisiana coast–1,400 square miles of ocean floor as bereft of life as an Arizona desert. The dead zone would be smaller except that Louisiana, like America as a whole, has lost a third of its coastal wetlands to economic development. Wetlands filter out impurities, much as the liver does for the human body. They also perform a second vital ecosystem function, acting as buffers that absorb and diminish the giant waves that hurricanes generate before they strike inland. Louisiana’s loss of wetlands helps explain why the floods Katrina unleashed ended up overrunning 466 chemical factories, thirty-one Superfund sites and 500 sewage treatment plants, according to the Times-Picayune and the Houston Chronicle, leaving behind a toxic soup whose long-term health effects are incalculable.

Despite these horrors some leading environmentalists see a potential silver lining in Katrina: They believe it may finally awaken the United States from its environmental complacency, especially about global warming. “Sea-level rise and increased storm intensity are no longer abstract, long-term issues but are associated with horrific pictures seen on television every evening,” says Christopher Flavin, president of the Worldwatch Institute.

Yes, the Bush Administration and its right-wing allies will continue to deny that global warming exists and resist cutting carbon emissions. But global warming foot-draggers have succeeded in the past largely because the public was confused about whether the problem really existed. That confusion was encouraged by the mainstream media, which in the name of journalistic “balance” gave equal treatment to global warming skeptics and proponents alike, even though the skeptics represented a tiny fringe of scientific opinion and often were funded by companies with a financial interest in discrediting global warming. Katrina, however, may mark a turning point for the media as well as the public.

“The reaction has been more positive than any time in the sixteen years that I’ve been trying to make noise about global warming,” says Bill McKibben, author of the 1989 classic The End of Nature. The day after Katrina hit, McKibben wrote an article for TomDispatch.com arguing that the devastation of New Orleans was, alas, only the first of many global warming disasters destined to strike in the twenty-first century. When McKibben appeared on radio shows to discuss the article, he says, “Everyone, and I mean everyone, who called in said, Thank heaven someone is saying this stuff, because it’s what I’m thinking about all the time now.”

“Had I said this stuff two years ago, the reactions would have ranged from skeptical to hostile, except for the liberal outlets,” says Ross Gelbspan, whose Op-Ed article in the Boston Globe arguing that Katrina’s “real name was global warming” led to forty-five media appearances. Gelbspan, who exposed industry funding of global warming skeptics in his book The Heat Is On, adds, “Even a couple of hostile, initially antagonistic right-wing talk-show hosts were drawn into the discussion–and their remarks turned from provocative to curious to sympathetic.”

“There aren’t many reporters left who believe the skeptics,” says Phil Clapp, president of the National Environmental Trust. Clapp credits the joint statement issued by eleven of the world’s national academies of science (including America’s), before last June’s meeting of the G-8 nations, declaring that global warming was a grave danger requiring immediate attention. “You may not have seen headlines screaming that Katrina was caused by global warming,” Clapp adds, “but every reporter I’ve talked to has come to the position in their own mind that we have to prepare for global warming’s effects.”

But what journalists think in their own minds matters less than what they put on the air and in the papers. And given the gravity of the situation, screaming headlines are warranted. It’s true that global warming can’t be definitively blamed for one particular weather event; weather is the product of too many different factors to allow such specificity. Seizing on this fact, skeptics now trumpet scientific studies that portray Katrina as simply a manifestation of a natural long-term pattern in which first strong then weak hurricanes predominate. That pattern is real, but it doesn’t invalidate global warming; the two trends can co-exist. The scientists at RealClimate.org offer a useful analogy: Imagine a set of dice loaded so that double sixes come up twice as often as normal. If the dice are then rolled and double sixes do come up, the loading may or may not be responsible for the result; after all, regular dice sometimes yield double sixes, too. All that’s certain is that over time the frequency of double sixes will increase. Likewise, Katrina might have been an extra-powerful hurricane even if humanity had never emitted a single greenhouse gas. But over time, humanity’s loading of the climatic dice guarantees that there will be more killer hurricanes like Katrina. We’d better get ready, and quickly.